One popular type of beverage can in common use today is made of recyclable aluminum or an aluminum alloy and features a top formed with a normally flush, bend-down segment or tongue which is defined by an indented, weakened marginal break line extending partially through the thickness of the metal of the can top. A normally flush pull ring or tab is connected by a rivet to the pivot end portion of the bend-down tongue and is operable when manually pulled to break the marginal edge of the tongue free from the remainder of the can top and pivot the tongue downwardly into the can, thus forming an opening in the can top through which a beverage or other liquid in the can may be out-poured. Recyclable cans of the aforesaid type have a desirable advantage of retaining the pull tab and the associated bend-down tongue, but have a distinctly undesirable feature in that, upon opening of the can, the exposed and possibly germ-carrying upper surface of the bend-down tongue is plunged downwardly and immersed in the contents of the can with possible contaminating effects. Recyclable aluminum cans are also more slowly biodegradable and considerably more expensive than a comparable size steel can.
Another type of so-called easy-opening beverage can in common use today utilizes a steel body and top, wherein the top is formed with a generally radially oriented opening which is normally covered and sealed by a rupturable synthetic resin film adhesively secured to the underside of the can top. A pull tab in the form of a second layer or film of synthetic resin is adhesively applied to the outer surface of the can top in covering relation to the opening and in cohesive engagement with the area of the underlying, rupturable film which underlies the opening. When it is desired to open the can, the pull tab is "peeled" radially from the can top thus rupturing the portion of the underlying synthetic resin film in the area of the opening to permit the contents of the can to be outpoured through the opening.
While the aforesaid synthetic resin film-sealed steel cans are comparatively less expensive than recyclable alumimum cans, they lack the ability to retain their pull tabs upon opening of the can and are not suitable containers for carbonated beverages or other liquids under super atmospheric pressure.